1. Field of the Invention
The invention generally relates to a rotating electrical machine, and more particularly, a rotating electrical machine having a structure for cooling a coil end portion.
2. Description of the Related Art
International Publication Number WO 2004/19468 describes a related rotating electrical machine which is a vehicle motor that aims to efficiently cool a stator that generates heat from a coil.
In the vehicle motor described in International Publication Number WO 2004/19468, the stator is covered by a coil end cover that surrounds both end surfaces of the coil and the stator core. Cooling oil supplied by an oil pump is filled inside the coil end cover. Further, this vehicle motor has cooling passages that communicate the coil end cover that surrounds one end surface of the stator core with the coil end cover that surrounds the other end side of the stator core to enable coolant to contact the stator windings.
Also, Japanese Patent Application Publication No. 2005-261084 (JP-A-2005-261084) describes a motor cooling structure that aims to improve cooling efficiency. The motor cooling structure described in JP-A-2005-261084 has i) a circumferential cooling passage that is formed on both ends in the axial direction of the stator so that coolant directly contacts a portion of the coil end, and ii) an axial cooling passage that is formed in the axial direction of the stator and communicates the circumferential cooling passages on both ends of the stator.
Also, Japanese Patent Application Publication No. 8-250881 (JP-A-8-250881) describes a cooling structure of a heat-generating component that aims to uniformly and efficiently cool that heat-generating component, regardless of where that heat-generating component is mounted. The cooling structure of the heat-generating component described in JP-A-8-250881 is provided with a turbulence promoting portion (a metal block body) on a portion facing the heat-generating component. In this turbulence promoting portion, coolant collides with a turbulence promoting member which creates turbulence that enables the heat-generating component, which is arranged directly below the turbulence promoting portion, to be uniformly cooled.
Also, Japanese Patent Application Publication No. 2007-295698 (JP-A-2007-295698) describes a stator of a rotating electrical machine that aims to obtain sufficient joint strength without melting an insulating member. In the rotating electrical machine described in JP-A-2007-295698, the end portion of a coil wound around the teeth of a stator core and the end portion of a coil wound around other teeth are connected together by a bus bar.
Moreover, Japanese Patent Application Publication No. 2005-117845 (JP-A-2005-117845) describes a rotating electrical machine cooling apparatus that aims to efficiently cool a rotating electrical machine mounted in a vehicle using a cooling medium, while maintaining the durability of that cooling medium. In the rotating electrical machine cooling apparatus described in JP-A-2005-117845, a cooling oil dripping portion for dripping cooling oil on a stator is provided in a housing that houses the stator.
In the vehicle motor described in International Publication Number WO 2004/19468, a cooling passage for supplying coolant so that the coolant contacts the stator winding is formed radially inward of the stator core. However, when oil supplied inside the coil end cover is unable to smoothly flow from one end surface of the stator core to the cooling passage, the cooling efficiency of the coil may not be able to be sufficiently improved.